| Hawaii Preparatory Academy | Academic & Science |
| IEEE Haraden Pratt Award | Academic & Science |
| Hartshorne Plunkard Architecture | Academic & Science |
| High-Purity Aluminium | Business |
| Health Plan Advisories | Business |
| Heritage Preservation Association | Community |
| Homeschool Performing Arts | Community |
| Hurlingham Polo Association | Community |
| Hollywood Professional Association | Community |
| High Performance Addressing | Computer Assembly Language |
| High Performance Architecture | Computer Hardware |
| High Performance Array | Computer Hardware |
| Host Protected Area | Computing |
| Homeplug Powerline Alliance | Computing |
| High Performance Analog | Computing |
| High-power Amplifier | Electronics |
| High Pressure Air | General |
| Hypothamic Pituitary Adrenal | General |
| Hide Powder Azure | General |
| Home Price Appreciation | General |
| Horizontal Pod Autoscaling | General |
| High Pressure Awesome | General |
| High Priority Access | General |
| Happily Performing Autos | General |
| High Performance Alloy | General |
| High Priority Area | General |
| Honda Personal Assistant | General |
| Haraden Pratt Award | General |
| Hydraulic Project Approval | General |
| Humanity Photo Awards | General |
| Human Platelet Antigens | General |
| Hypothalamo Pituitary Adrenal | General |
| Human Protein Atlas | General |
| Honors Point Average | General |
| Hereford Pale Ale | General |
| Highly Professional Advisors | General |
| Helping people achieve | General |
| Hypothalamus Pituitary Adrenal | General |
| High Performance Aluminium | General |
| Human Powered Aircraft | General |
| Hydrocephalic Procarbazine Acetate | General |
| Horizontal Position Absolute | General |
| Horizontal Pod Autoscaler | General |
| Horticulture Produce Agreement | General |
| High Purity Alumina | General |
| Hypothalamus Pituitary and Adrenal | General |
| Horticulture Produce Agreements | General |
| Health Protection Agency | Governmental |
| Hawaii Paroling Authority | Governmental |
| Health Protection Agency (BRITISH) | Governmental |
| Hamburg Port Authority | Governmental |
| Harry Potter Alliance | Governmental |
| Hollywood Post Alliance | Governmental |
| Houston Paralegal Association | Governmental |
| Homeowners Protection Act | Governmental |
| Haryana Police Academy | Haryana Government |
| HAMPAPURA | Indian Railway Station |
| Hidrocarburi Policiclice Aromatice | International |
| Health Plan Administrator | Jobs |
| Hectopascal | Measurement Unit |
| Hypothalamic - Pituitary - Adrenal (axis) | Medical |
| Health Promotion Administration | Medical |
| Health Plan Accreditation | Medical |
| Health Professions Academy | Medical |
| HaemangioPericytomA | Medical |
| Health Promotion Advisor | Medical |
| His-Purkinje activity | Medical |
| Human Platelet Antigen | Medical |
| hyperphenylalaninaemia | Medical |
| Hypertrophic Pulmonary Arthropathy | Medical |
| Hypothalamic Pituitary Axis | Medical |
| Hypothalamic-Pituitary-Adrenal | Medical |
| Health Protection Agency (UK) | Medical |
| hypothalmic-pituitary-adrenal axis | Medical |
| Health Policy and Administration | Medical |
| Health Professions Advising | Medical |
| Healthcare Professional Agency | Medical |
| Health promotion agency | Medical |
| Health Professions Authority | Medical |
| Health Poverty Action | Medical |
| Head of Processing Activity | Military and Defence |
| Head of Procurement Activity | Military and Defence |
| Ha'apai, Tonga Islands, South Pacific | Regional |
| Hop Products Australia | Regional |
